<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* 样式重置 */
        * {
            margin: 0;
            padding: 0;
        }

        .main-box {
            /* 网页安全区 */
            width: 1200px;
            /* 设置外边距自动，居中当前模块 */
            /* margin: auto; */
            margin: 0 auto;


            height: 200px;
            background-color: salmon;
        }
    </style>
</head>

<body>
    <div class="main-box">
        主区域
    </div>
</body>

</html>